Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.

Erik M. Conway, Historian, Jet Propulsion Laboratory

After a midcourse correction on 1 April, Luna 10, the second of two hastily prepared Soviet Ye-6S probes (that is, the backup), successfully entered lunar orbit two days later at 18:44 UT, thus becoming the first human-made object to go into orbit the Moon. A 245-kilogram instrument compartment separated from the main bus, which was in a 350 x 1,000-kilometer orbit inclined at 71.9° to the lunar equator.

The spacecraft carried a set of solid-state oscillators that had been programmed to reproduce the notes of the Internationale so that it could be broadcast live to the 23rd Communist Party Congress. During a rehearsal on the night of 3 April, the playback went well, but the following morning, controllers discovered a missing note and played the previous night's tape to the assembled gathering at the Congress, claiming it was a live broadcast from the Moon.

Luna 10 conducted extensive research in lunar orbit, gathering important data on the weakness of the Moon's magnetic field, its radiation belts, and the nature of lunar rocks (which were found to be comparable to terrestrial basalt rocks), cosmic radiation, and micrometeoroid density. During that time, tracking data showed that the spacecraft's orbit was being distorted by strong irregularities in the Moon's gravity field, providing the first evidence that the Moon's internal composition wasn't uniform. Last contact was on 30 May 1966.

Key Dates

31 Mar 1966: Launch

3 Apr 1966: Lunar Orbit Insertion

Status: Successful

Fast Facts

Luna 10 was the first artificial object to orbit the Moon.

The probe also beamed the song, "The Internationale" to the 23rd Congress of the Communist Party, though what the delegates actually heard was a recording from the previous night's rehearsal.

The probe also beamed the song, "The Internationale" to the 23rd Congress of the Communist Party, though what the delegates actually heard was a recording from the previous night's rehearsal.